From U.S. Pat. No. 6,512,843, a method is known wherein adjacent dies are compared to one another. Herein, the exposures and the dies each have the same size so that they are comparable. Only the edge areas are compared at irregular intervals. In this approach, however, the full camera exposure capabilities are usually not considered. The camera often records much more than is actually necessary for subsequent comparison. This leads to an unnecessary increase in data, which in turn leads to the system being slowed down.
U.S. Pat. No. 7,184,612 discloses a method and an apparatus for parallel processing of data in a wafer inspection system, wherein no communication or synchronization is needed between the individual process nodes. The approach is based on hardware, wherein the detection area is subdivided into a fixed number of blocks due to the fact that the number of groups of process nodes is also fixed due to fixed wiring.
From U.S. Pat. No. 7,215,808, an image processing system for error detection is known. The system comprises a plurality of processors for recording image data from a substrate. The analysis of one or more selected portions of such an image can also be carried out to see whether the substrate has a defect. The system comprises a plurality of buses to connect the individual processors to each other, wherein the data transfer speed per bus is 50 gigabits per second or more, and the error rate is below about 10−16. Again, this is a hardware realization with a fixed number of buses, processors and lines.
From U.S. Pat. No. 7,221,992, a method and an apparatus are known for parallel data processing for error detection in a wafer inspection system. A data distribution system comprises a plurality of data distribution nodes, which are interconnected via a plurality of data transmission paths. This configuration enables data collected by any desired type of detector to be forwarded to respective ones of the plurality of process nodes. This, in turn, enables the implementation of a plurality of possible algorithms for error analysis.
German patent application DE 103 07 373 A1 discloses a method and an apparatus for optical analysis of wafers, the structures of which have been created by SAWs. The invention takes into account that depending on the stepper and the size of the dies (design), the size of the SAW varies substantially. Generally, it cannot be expected that an SAW can be imaged with one camera image. This is why an SAW is preferably subdivided into regular, equally sized logical portions (SAW segments). Each logical SAW segment has a SAW segment index associated with it. An image field of the camera can only cover a certain number of these SAW segments. Each segment of an image field, also referred to as an image field segment, has an index associated with it, also referred to as an image field segment index.
German patent application DE 103 31 593 A1 discloses a method for defect segmenting in structures on semiconductor substrates. After recording an image of a semiconductor substrate, identical structures or structural elements are subtracted from one another. The resulting difference function is compared with a top and bottom threshold for the detection of defects.
German patent application DE 103 43 148 A1 discloses a method and an apparatus for inspecting a wafer, wherein at least one segment of a surface of a wafer is illuminated, an image of the illuminated segment is detected by an image detection means, at least one image area in the detected image is determined, and a size of the image area of the image detection means is changed on the basis of the at least one image area. For determining the image area, a pattern detection software looks for characteristic structures in the detected image. By changing the image field size, optionally either the throughput or the resolution of the wafer inspection apparatus can be optimized, and the image field can always be optimally adapted to the shot size of the wafer.
German patent application DE 10 2005 027 120 A1 discloses a method for inspecting a wafer, wherein the wafer has a first area of periodically arranged SAWs and at least one second area of SAWs displaced with respect to the first area. The method shows the process steps of optically recording the first area of the wafer by moving an imaging window in the period direction, displacing the imaging window relative to the wafer, optically recording the second area of the wafer by moving the displaced imaging window in the period direction, and evaluating the image by comparing partial images.